The Neutrino Oscillation Industry*

*Title taken from Maury Goodman's websitewww.neutrinooscillation.org

Funny math bit you may not have thought about

sin2θ

is NOT just for angles and trigonometry,waves and other oscillating functions

and doesn't have to be a function of kx or ωt.

It is also can be used to represent a constantwhose value must be between 0 and 1

which is a property it shares with a probability.

Furthermore, this constant automatically includesits probability partner (1 – P) = (1 – sin2θ) = cos2θ

So we could use either sin2θ or just θas a constant of nature driving either/or probability.

Standard Model of Elementary Particles

What does a neutrino look like in our detector?

distance along beam axis36 cm

Strange question.How does an electron look? Proton? Gold nucleus?

Question: if we build experiments to detect neutrinoswhat will we see?

Neutrino interaction, May 2010from MINERvA experiment data

A picture of a typical neutrino interaction

muon neutrino muon

muon from pion decay

pion

Carbonnucleus

v + n → μ- + π+ + nbut neutral particles are unseen muon

pion

The neutrino turned into a muon, and made a pion

distance along beam axis36 cm

A picture of a typical neutrino interaction

muon neutrino muon

muon from pion decay

pion

Carbonnucleus

v + n → μ- + π+ + nbut neutral particles are unseen muon

pion

The neutrino turned into a muon, and made a pion

distance along beam axis36 cm

New Standard Model?

+ string theory?+ extra dimensions?– missing Higgs particle?+ higher order group theory?+ Branes?+ New particles?+ New forces?+ Quarks not fundamental?+ Sub-structure to electron?+ Theory of Everything?+ Theory of Almost Everything?

How do we tell which are right?Or are they all science fiction or fantasy?

New Standard Model: Concrete Example

1012

109

106

103

1

10-3

Higgs particle above this line is standardSupersymmetry particle?Super-massive Right-Handed Neutrino?

quarks

charged leptons<- electron

neutrinos

particlemasses

eV/c2

ExponentialScale

We list these massesin the back of textbooks.

The standard modeltakes the textbook numberbut does not EXPLAIN why

A satisfactory “new model”should explain this structure.

Especially why the neutrinosare way down here.

Current bestaccelerators

du

Standard Cosmology

Post-modern Cosmology

Nobel Prize >2020 ?

Nobel Prize >2030 ?

Matter-Antimatter asymmetry (CP violation)

How to explain that our region of the universeseems to be nearly all matter, not anti-matter?

Actually there is a second boxwith anti-electrons (positrons)anti-up and anti-down quarks

and so on. We know these well.They are perfect opposites,

but actually not quite perfect!

But my shoes are not madeof anti-electrons.

My kids aren't made ofanti-protons and anti-neutrons.

Curious things about Quantum TheoryThat are important for the rest of the story.

A non quantum example of a quantum phenomenon.

Three ice creams.

You can describe them in terms of flavor:Strawberry, Vanilla, Chocolate.

You can describe them in terms of color:Red, White, Brown.

Curious things about Ice CreamsThat are important for the rest of the story.

“Flavor” comes from a perfume factory in New Jersey“Color” comes from a differentchemistry factory elsewhere in New Jersey.

“Red” does not have to taste like chocolate.There is no reason to think Vanilla won't be brown.

Quantum mechanics, particle physics standard modelAllow mixups like this to happen.

Experimentally figure out what New Jersey is doing!

More curious things about Ice CreamHypothesis: Darker colored ice cream will melt faster (decay)

regardless of its flavor.

We could start with 1 million ice creams, each is one combinationof color and flavor and take a two separate surveys:

1/3 S; 1/3 V; 1/3 C and also 1/3 W; 1/3 R; 1/3 B

Now all the brown ones melt away, and we look at whats left. 1/4 S; 1/2 V; 1/4 C and also 1/2 W; 1/2 R

If this is what New Jersey delivered, this is what you get...conclude that Brown was made of half strawberry, half chocolateYou know this by the deficit of S&C but no deficit of Vanilla!

Measured the flavor of a sample of many ice creams as a function of TIME (before and after)

for ice creams that are just sitting there minding their own business.

More curious things about NeutrinosThe physics of neutrinos is NOT the physics of melting or decaying.

It is the physics of superposition and interfering waves.

A neutrino oscillation experiment creates neutrinos as a flavor.

Experiments taste flavor.

But each neutrino also has one of three masses

(mass, not color!)

and the folks in New Jersey naturejumble flavor and mass

according to some secret formula.

Probability(νμ to ντ) = sin22θ sin2(1.27 Δm2 L/E)units: L in km, E in GeV, m in GeV/c2

m22 - m32

Measure L and E for each eventFit two parameters to the whole group of data.

Look for disappearance of muon neutrinos

Amplitude of maximum tauJust a number ≤ 1.0

IS NOT an oscillating term

Where in (travel Length)/(Energy)

does maximum tau occur?Really these are proper

oscillations in TIME

The secret formula!

If we create mu flavor

Neutrino detection

We detect things at Soudan with 5 thousand tons of instrumented iron. This device can see νμ very well and νe sorta okay

Neutrino flavor change

We produce νμ and detect νe and νμ .Previous experimental results (1998, 2005) suggest:

1. this experiment will see fewer νμ than we sent.AND

2. this experiment will see zero or almost zero νe.

BECAUSE Some of the νμ changed to ντ .

Remember: Ice cream melting does not do this, but quantum mechanical particles can do this.

Neutrino oscillations: MINOS experiment

Situation: We create νμ at Fermilab with a machine that only creates νμ .

Send them through the earth to Soudan, MN.The “L” in our formula is 735 km

(really 2.5 milliseconds traveling at the speed of light).

How does MINOS see neutrinos?

We don't see the neutrinos themselves

We see the result of their interactionwith rock, steel, or plastic.

They communicate flavornot by tasting them:

a muon neutrinoproduces a muonin the interaction

We count muons.We count muonsreally, really well.

How does MINOS see muons?

Photo of ascintillator strip

41 mm10 mm

Cross-section photo of two scintillator strips with fibers glued into grooves.

Scintillator graphicscourtesy of Doug Michael, Caltech

Ionization produces light in scintillator

Fiber optics route light to a set of light sensors

High Voltage in, electrical pulse out

Thousands of pulses all come together here

Fermilab beam ->

Ask a computer to reconstruct it all.Side view Front (Fermilab) view

This one started in rockproduced a muon

which went into the front of detector

and stopped 2/3 through

What MINOS sees after four years of beam

What MINOS sees after four years of beam

Ratio of data to red prediction and best fit

What MINOS sees with the best fit to the formula

Where in energythe maximumeffect is seentells us aboutthe oscillating

term and Δ(m2)

How deep themaximum effecttells us about theamplitude term

sin22θ

Probability(νμ to ντ) = sin22θ sin2(1.27 Δm2 L/E)

units: L in km, E in GeV, m in GeV/c2

Higher E

Wherein Energy Is the dip

Lower E

How deep is the dip?Shallow Deep

What we measure for nature's parameters

More about particle masses

1012

109

106

103

1

10-3

quarks

charged leptons<- electron

neutrinos

Turns out neutrino massesare very difficult to measureusing regular strategies likeconservation of energy andconservation of momentum

Current bestaccelerators

du

Upper limit on neutrino mass

From direct searches

We know neutrino mass is hereBecause we measure

|m22-m32| ~ 2.5x10-3 eV2

particlemasses

eV/c2

ExponentialScale

We could see electrons instead of mu or tau?

The secret formula assumes mu to tau oscillationsbecause nobody had seen mu to electron oscillations

so this is either very rare, or it never happensThe oscillation hypothesis says it could (should?)

MINOS is able to seeelectrons, sorta.

In fact, we expect someelectron like things

even without oscillationsbecause the beamisn't actually pure.

And even still, we seeextra! Sorta.

Electron-like events in MINOS

Next steps in neutrino oscillations: NOvAMINOS is barely able to search for electron appearance

NOvA is optimized for this search and/or measurement.Located in Ash River, Minnesota

Hmm. T2K in Japan is a competing experiment

Next steps in neutrino oscillations:LBNE and search for CP violation

Radically different detector technology.Longer baseline. More powerful beam.

Combine numu disappearance, nue appearanceOptimized to look for differences between

neutrino oscillations and anti-neutrino oscillations

How can we see that this is maximally odd?

no mixing at all.zero sin22θ for all threecombinations θ12 θ13 θ23

slight mixing among allall sin22θ slightly above zero

full mixing among allall sin22θ very close to 1

two mixings are maximaltwo sin22θ are slightly less than oneand the other is slightly more than one

How can we see that this is maximally odd?

no mixing at all.zero sin22θ for all threecombinations θ12 θ13 θ23

slight mixing among allall sin22θ slightly above zero

full mixing among allall sin22θ very close to 1

two mixings are maximaltwo sin22θ are slightly less than oneand the other is slightly more than one

BORING

How can we see that this is maximally odd?

no mixing at all.zero sin22θ for all threecombinations θ12 θ13 θ23

slight mixing among allall sin22θ slightly above zero

full mixing among allall sin22θ very close to 1

two mixings are maximaltwo sin22θ are slightly less than oneand the other is slightly more than one

BORING

Mostly Dull

How can we see that this is maximally odd?

no mixing at all.zero sin22θ for all threecombinations θ12 θ13 θ23

slight mixing among allall sin22θ slightly above 0.0

full mixing among allall sin22θ very close to 1.0

two mixings are maximaltwo sin22θ are slightly below 1.0and the other is slightly above 0.0

BORING

Mostly Dull

Mostly Interesting

! ? !

Conclusions

What we now understand about neutrinosis already beyond the standard model

Neutrino oscillations arise from a pretty keenquantum mechanics feature (but not unique): mixing

This only works if neutrinos have non-zero mass.

The mixing pattern is not small, is not boring.Its about as interesting as it possibly could be.

We are pushing experiments to know moreto figure out what the new standard model

should look like

One other ingredient is needed for the future

All these experiments depend on this prediction:how many neutrinos we will see in our detector

GeV

prediction

The MINERvA experimentFine-grained detectorTracking and CalorimetryHigh Rate

Put in front of MINOS near detector

Detector is mostly plastic

We get a much better viewof the neutrino interactions!

Data started this past year

ν

What does a neutrino look like in MINERvA?A muon neutrino

comes in,A charged muon

goes out.

And (probably) a pionup + down quark

or (maybe) a proton

0 15 30 45 60 cmz coordinate

30

60

90

120

180

0

x co

ordi

nate

(cm

)

150

muon

pion

Candidate neutral pion production

muon goes out the back

two neutral particleslook like EM showers,

but asymmetricenergy sharing.

Except for that muon,this showery thing

would (could)fool MINERvA or NOvA

into thinking we sawan electron neutrino.

muon

em shower

little em shower

0 15 30 45 60 cmz coordinate

30

60

90

120

180

0

x co

ordi

nate

(cm

)

150

What was the story here?

Neutrino experiments like MINOS have demonstratedthat neutrinos have very small, but non-zero mass.

They participate in a curious, quantum mixing processthat jumbles “flavor” and “mass” properties

There is something blatant and asymmetric to howthe three flavors mix or not mix, in particularthe probability parameters sin22θ are either

close to maximal (one) or close to minimal (zero)

If there is substantial CP violation in the leptonsand if we see extra electrons in a beam like these,

then we've got the matter-antimatter mystery solved.

The probability forflavor change

for different energiesat the MINOS distance

Different values for

sin22θ

Correspond to thedepth of the effect

sin22θ = 0.2

sin22θ = 1.0

Again the probabilityfor flavor change

for different energies at the MINOS distance

Different values for

|m22-m32|

Correspond to thelocation in energy

of the maximum effect

Why neutrino oscillation industry?

Look at the timeline of what is happening in neutrino oscillations experiments:

In the 1960s and 1970san experiment in the Homestake mine

says neutrinos from the sun are missing.No one knew why.

In the 1980sTwo underground experiments:

IMB, Kamiokandeclaim muon neutrinos from cosmic rays are missing

Neutrino Oscillation Industry: 1990s

Some experiments look for disappearing neutrinosfrom reactors and don't see anything unusual.

The follow-up Super-Kamiokande experiment(Remember Alex Habig's talk) confirms the earliercosmic ray results with enough data to really mapout the disappearance clearly. (1998)

Even before Super-K was operational, plans werestarted to send a beam to that experiment (K2K).

Neutrino Oscillation Industry: 2000s

The K2K experiment starts operation,and takes data from 1999 until 2004.

The MINOS experiment starts in 2005,and plans to have a data set as good as

K2K in only 6 months (and run for years after)

The Sudbury experiment in Canadasystematically confirms the “solar” neutrino result

is consistent with neutrino oscillations...

The Kamland experiment finds neutrinosfrom nuclear reactors are missing also.

A quick tour of the neutrino oscillation industry?

Our formula had only muon and tau flavors.

But there are actually three different flavor combinations

Use all kinds of neutrino sources:The Sun

Nuclear ReactorsAccelerator Beams

The Earth

And many kinds of detectors to see them!

1970's: Homestake and solar electron neutrinos

Looked for electron neutrinos from the sun.

Observed only 1/3of what was expected.

Nobel Prize 2002Ray Davis

1980's: Kamiokande and IMB experiments

Hints thatmuon neutrinosfrom cosmic raysare not seen

(Saw roughly half)

IMB detector in the U.S.

Nobel Prize 2002M. Koshiba (Kamiokande in Japan)

1990's: Super-Kamiokande

Not only do we NOT seeall the muon neutrinosbut we DO seeall the electron neutrinos

But muon neutrino“disappearance”goes as L/E

The neutrino oscillationformula might be right.

Decaying ice cream model is probably wrong.

2000's: Better solar measurements

SNO experiment underground Sudbury, Ontario, Canada

High precision measurementsof electron neutrinosfrom the sun.

Data is consistent withelectron neutrinos changingto both muon neutrinosand tau neutrinos equally.

2000's: Better reactor measurements

Kamland experiment in Japan measures electron neutrino disappearance

from nuclear power reactors in Japan.

They also see neutrinos from radioactive decay in the Earth.

2010's: Even Better MeasurementsNew accelerator experiments NOvA (U.S.) and/or T2K (Japan)

In US, use existing NuMI beamBuild a new far detectorin Northern Minnesota.

In Japan, use existing Super-Kbuild new beam in Tokai

2010's: Even Better MeasurementsNew reactor experiment at Daya Bay (China)

Put Kamland-like detectors here in this mountain

Neutrino Oscillation Industry: 2010s

An era of precision neutrino measurements:

One or two followup beam experiments:NOvA in the US, and T2K in Japan.

One or two followup reactor experiments:Braidwood in the US, Daya Bay in China

(And a small one, Double Chooz, in France)

Possible plans for a super-followup experiment?

The 2005 K2K experiment in Japan

250 km250 km

K2K muon neutrino data from 1999 to 2004

0 1 2 3 4 5Reconstructed neutrino energy (GeV)

Expected shapeBest Fit

Neutrino flavor change: K2K experiment 2005

We expected 150 νμ, but only saw 100 νμ !

What happened to theother 50?

They did not show up as electron neutrinos.

(In this graph:we see 57, expected 80)

How

man

y

What happened in Japan?

The neutrinos that were sent changed to

tau-flavor neutrinos

this is the simplest explanation,(but possibly incorrect)